In the C FE, c_parser_statement_after_labels passes "xloc" to
c_finish_return, which is the location of the first token
within the returned expression.
Hence we don't get a full underline for the following:
diagnostic-range-bad-return.c:34:10: warning: function returns address of local
variable [-Wreturn-local-addr]
return &some_local;
^
This feels like a bug; this patch fixes it to use the location of
the expr if available, and to fall back to xloc otherwise, giving
us underlining of the full expression:
diagnostic-range-bad-return.c:34:10: warning: function returns address of local
variable [-Wreturn-local-addr]
return &some_local;
^~~~~~~~~~~
The testcase also adds some coverage for underlining the
"return" token for the cases where we're warning about th
erroneous presence/absence of a return value.
As an additional tweak, it struck me that we could be more
user-friendly for these latter diagnostics by issuing a note
about where the function was declared, so this patch also adds
an inform for these cases:
diagnostic-range-bad-return.c: In function 'missing_return_value':
diagnostic-range-bad-return.c:31:3: warning: 'return' with no value, in
function returning non-void
return; /* { dg-warning "'return' with no value, in function returning
non-void" } */
^~~~~~
diagnostic-range-bad-return.c:29:5: note: declared here
int missing_return_value (void)
^~~~~~~~~~~~~~~~~~~~
(ideally we'd put the underline on the return type, but that location
isn't captured)
This latter part of the patch is an enhancement rather than a
bugfix, though FWIW, and I'm not sure I can argue this with a
straight face, the tweak was posted as part of:
"[PATCH 16/22] C/C++ frontend: use tree ranges in various diagnostics"
in https://gcc.gnu.org/ml/gcc-patches/2015-09/msg00745.html
during stage 1. Hopefully low risk, and a small usability improvement;
but if this is pushing it, it'd be simple to split this up and only
do the bug fix.
Successfully bootstrapped®rtested on x86_64-pc-linux-gnu;
adds 12 PASS results to gcc.sum.
OK for trunk for stage 3?
gcc/c/ChangeLog:
* c-parser.c (c_parser_statement_after_labels): When calling
c_finish_return, Use the return expression's location if it has
one, falling back to the location of the first token within it.
* c-typeck.c (c_finish_return): When issuing warnings about
the incorrect presence/absence of a return value, issue a note
showing the declaration of the function.
gcc/testsuite/ChangeLog:
* gcc.dg/diagnostic-range-bad-return.c: New test case.
---
gcc/c/c-parser.c | 3 +-
gcc/c/c-typeck.c | 28 ++++++++----
gcc/testsuite/gcc.dg/diagnostic-range-bad-return.c | 52 ++++++++++++++++++++++
3 files changed, 74 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/diagnostic-range-bad-return.c
diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index e149e19..933a938 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -5108,7 +5108,8 @@ c_parser_statement_after_labels (c_parser *parser,
vec<tree> *chain)
location_t xloc = c_parser_peek_token (parser)->location;
struct c_expr expr = c_parser_expression_conv (parser);
mark_exp_read (expr.value);
- stmt = c_finish_return (xloc, expr.value, expr.original_type);
+ stmt = c_finish_return (EXPR_LOC_OR_LOC (expr.value, xloc),
+ expr.value, expr.original_type);
goto expect_semicolon;
}
break;
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index b93da07..c314f08 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -9546,24 +9546,36 @@ c_finish_return (location_t loc, tree retval, tree
origtype)
if ((warn_return_type || flag_isoc99)
&& valtype != 0 && TREE_CODE (valtype) != VOID_TYPE)
{
+ bool warned_here;
if (flag_isoc99)
- pedwarn (loc, 0, "%<return%> with no value, in "
- "function returning non-void");
+ warned_here = pedwarn
+ (loc, 0,
+ "%<return%> with no value, in function returning non-void");
else
- warning_at (loc, OPT_Wreturn_type, "%<return%> with no value, "
- "in function returning non-void");
+ warned_here = warning_at
+ (loc, OPT_Wreturn_type,
+ "%<return%> with no value, in function returning non-void");
no_warning = true;
+ if (warned_here)
+ inform (DECL_SOURCE_LOCATION (current_function_decl),
+ "declared here");
}
}
else if (valtype == 0 || TREE_CODE (valtype) == VOID_TYPE)
{
current_function_returns_null = 1;
+ bool warned_here;
if (TREE_CODE (TREE_TYPE (retval)) != VOID_TYPE)
- pedwarn (xloc, 0,
- "%<return%> with a value, in function returning void");
+ warned_here = pedwarn
+ (xloc, 0,
+ "%<return%> with a value, in function returning void");
else
- pedwarn (xloc, OPT_Wpedantic, "ISO C forbids "
- "%<return%> with expression, in function returning void");
+ warned_here = pedwarn
+ (xloc, OPT_Wpedantic, "ISO C forbids "
+ "%<return%> with expression, in function returning void");
+ if (warned_here)
+ inform (DECL_SOURCE_LOCATION (current_function_decl),
+ "declared here");
}
else
{
diff --git a/gcc/testsuite/gcc.dg/diagnostic-range-bad-return.c
b/gcc/testsuite/gcc.dg/diagnostic-range-bad-return.c
new file mode 100644
index 0000000..063fdf1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/diagnostic-range-bad-return.c
@@ -0,0 +1,52 @@
+/* { dg-options "-fdiagnostics-show-caret -Wreturn-local-addr" } */
+
+int *address_of_local (void)
+{
+ int some_local;
+ return &some_local; /* { dg-warning "function returns address of local
variable" } */
+/* { dg-begin-multiline-output "" }
+ return &some_local;
+ ^~~~~~~~~~~
+ { dg-end-multiline-output "" } */
+}
+
+void surplus_return_when_void_1 (void)
+{
+ return 500; /* { dg-warning "'return' with a value, in function returning
void" } */
+/* { dg-begin-multiline-output "" }
+ return 500;
+ ^~~
+ { dg-end-multiline-output "" } */
+/* { dg-begin-multiline-output "" }
+ void surplus_return_when_void_1 (void)
+ ^~~~~~~~~~~~~~~~~~~~~~~~~~
+ { dg-end-multiline-output "" } */
+}
+
+void surplus_return_when_void_2 (int i, int j)
+{
+ return i * j; /* { dg-warning "'return' with a value, in function returning
void" } */
+/* { dg-begin-multiline-output "" }
+ return i * j;
+ ~~^~~
+ { dg-end-multiline-output "" } */
+/* { dg-begin-multiline-output "" }
+ void surplus_return_when_void_2 (int i, int j)
+ ^~~~~~~~~~~~~~~~~~~~~~~~~~
+ { dg-end-multiline-output "" } */
+}
+
+int missing_return_value (void)
+{
+ return; /* { dg-warning "'return' with no value, in function returning
non-void" } */
+/* { dg-begin-multiline-output "" }
+ return;
+ ^~~~~~
+ { dg-end-multiline-output "" } */
+/* { dg-begin-multiline-output "" }
+ int missing_return_value (void)
+ ^~~~~~~~~~~~~~~~~~~~
+ { dg-end-multiline-output "" } */
+/* TODO: ideally we'd underline the return type i.e. "int", but that
+ location isn't captured. */
+}
--
1.8.5.3
